The present invention relates to apparatus for converting radiant solar energy to usable heat and, specifically, to apparatus for heating a fluid by using the solar energy incident upon a collector.
There are at present numerous systems available for heating a fluid by solar energy and most employ the basic idea that the fluid is moved through or passed over a portion of the system upon which radiant solar energy is incident. The fluid thereby being heated by the sun. Certain of the systems contain dual concentric glass tubes with a vacuum formed therebetween and with the fluid flowing through the innermost tube. A number of the tubes are then arranged in parallel with the ends interconnected, and a fluid flowing through the tubes is heated by the sunlight falling on the assembly. One major problem with this kind of system is that typically it must be fully assembled at the manufacturing facility and a completely assembled unit ultimately installed, usually on a roof. The size of the fully assembled units makes installation difficult and requires more manpower than is economically desirable. Additionally, many existing solar energy collector systems are formed in such a fashion that if one of the tubes is broken or malfunctions it is necessary to disassemble the entire unit in order to replace one glass tube. Another drawback of many of the known solar energy collectors is that generally they are complicated in that they require a large number of seals and the like in order to make them liquid tight. A problem which is also present in almost all solar collectors of this kind is that a certain amount of laminar flow of the working fluid is present which degrades optimum thermal energy transfer.